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-rw-r--r--include/axolotl/crypto.hh88
-rw-r--r--src/crypto.cpp223
-rw-r--r--src/libs.cpp5
-rw-r--r--tests/test_crypto.cpp100
4 files changed, 416 insertions, 0 deletions
diff --git a/include/axolotl/crypto.hh b/include/axolotl/crypto.hh
new file mode 100644
index 0000000..9691228
--- /dev/null
+++ b/include/axolotl/crypto.hh
@@ -0,0 +1,88 @@
+#include <cstdint>
+
+namespace axolotl {
+
+
+struct Curve25519PublicKey {
+ static const int LENGTH = 32;
+ std::uint8_t public_key[32];
+};
+
+
+struct Curve25519KeyPair : public Curve25519PublicKey {
+ std::uint8_t private_key[32];
+};
+
+
+Curve25519KeyPair generate_key(
+ std::uint8_t const * random_32_bytes
+);
+
+
+const std::size_t CURVE25519_SHARED_SECRET_LENGTH = 16;
+
+
+void curve25519_shared_secret(
+ Curve25519KeyPair const & our_key,
+ Curve25519PublicKey const & their_key,
+ std::uint8_t * output
+);
+
+
+struct Aes256Key {
+ static const int LENGTH = 32;
+ std::uint8_t key[32];
+};
+
+
+struct Aes256Iv {
+ static const int LENGTH = 16;
+ std::uint8_t iv[16];
+};
+
+
+std::size_t aes_pkcs_7_padded_length(
+ std::size_t input_length
+);
+
+
+void aes_pkcs_7_padding(
+ std::uint8_t const * input, std::size_t input_length,
+ std::uint8_t * output
+);
+
+
+void aes_encrypt_cbc(
+ Aes256Key const & key,
+ Aes256Iv const & iv,
+ std::uint8_t const * input, std::size_t input_length,
+ std::uint8_t * output
+);
+
+
+void aes_decrypt_cbc(
+ Aes256Key const & key,
+ Aes256Iv const & iv,
+ std::uint8_t const * input, std::size_t input_length,
+ std::uint8_t * output
+);
+
+
+const std::size_t HMAC_SHA256_OUTPUT_LENGTH = 32;
+
+
+void hmac_sha256(
+ std::uint8_t const * key, std::size_t key_length,
+ std::uint8_t const * input, std::size_t input_length,
+ std::uint8_t * output
+);
+
+
+void hkdf_sha256(
+ std::uint8_t const * input, std::size_t input_length,
+ std::uint8_t const * info, std::size_t info_length,
+ std::uint8_t const * salt, std::size_t salt_length,
+ std::uint8_t * output, std::size_t output_length
+);
+
+} // namespace axolotl
diff --git a/src/crypto.cpp b/src/crypto.cpp
new file mode 100644
index 0000000..c1ef88a
--- /dev/null
+++ b/src/crypto.cpp
@@ -0,0 +1,223 @@
+#include "axolotl/crypto.hh"
+#include <cstring>
+
+extern "C" {
+
+int curve25519_donna(
+ uint8_t * output,
+ const uint8_t * secret,
+ const uint8_t * basepoint
+);
+
+#include "crypto-algorithms/aes.h"
+#include "crypto-algorithms/sha256.h"
+
+}
+
+
+namespace {
+
+static const std::uint8_t CURVE25519_BASEPOINT[32] = {9};
+static const std::size_t AES_BLOCK_LENGTH = 16;
+static const std::size_t SHA256_BLOCK_LENGTH = 32;
+static const std::uint8_t HKDF_DEFAULT_SALT[32] = {};
+
+template<std::size_t block_size>
+inline static void xor_block(
+ std::uint8_t * block,
+ std::uint8_t const * input
+) {
+ for (std::size_t i = 0; i < block_size; ++i) {
+ block[i] ^= input[i];
+ }
+}
+
+
+inline static void hmac_sha256_key(
+ std::uint8_t const * input_key, std::size_t input_key_length,
+ std::uint8_t * hmac_key
+) {
+ if (input_key_length > SHA256_BLOCK_LENGTH) {
+ ::SHA256_CTX context;
+ ::sha256_init(&context);
+ ::sha256_update(&context, input_key, input_key_length);
+ ::sha256_final(&context, hmac_key);
+ } else {
+ std::memset(hmac_key, 0, SHA256_BLOCK_LENGTH);
+ std::memcpy(hmac_key, input_key, input_key_length);
+ }
+}
+
+
+inline void hmac_sha256_init(
+ ::SHA256_CTX * context,
+ std::uint8_t const * hmac_key
+) {
+ std::uint8_t i_pad[SHA256_BLOCK_LENGTH];
+ std::memcpy(i_pad, hmac_key, SHA256_BLOCK_LENGTH);
+ for (std::size_t i = 0; i < SHA256_BLOCK_LENGTH; ++i) {
+ i_pad[i] ^= 0x5C;
+ }
+ ::sha256_init(context);
+ ::sha256_update(context, i_pad, SHA256_BLOCK_LENGTH);
+ std::memset(i_pad, 0, sizeof(i_pad));
+}
+
+
+inline void hmac_sha256_final(
+ ::SHA256_CTX * context,
+ std::uint8_t const * hmac_key,
+ std::uint8_t * output
+) {
+ std::uint8_t o_pad[SHA256_BLOCK_LENGTH];
+ std::memcpy(o_pad, hmac_key, SHA256_BLOCK_LENGTH);
+ for (std::size_t i = 0; i < SHA256_BLOCK_LENGTH; ++i) {
+ o_pad[i] ^= 0x36;
+ }
+ ::SHA256_CTX final_context;
+ ::sha256_init(&final_context);
+ ::sha256_update(&final_context, o_pad, SHA256_BLOCK_LENGTH);
+ ::sha256_final(context, o_pad);
+ ::sha256_update(&final_context, o_pad, SHA256_BLOCK_LENGTH);
+ ::sha256_final(&final_context, output);
+ std::memset(o_pad, 0, sizeof(o_pad));
+}
+
+} // namespace
+
+
+axolotl::Curve25519KeyPair axolotl::generate_key(
+ std::uint8_t const * random_32_bytes
+) {
+ axolotl::Curve25519KeyPair key_pair;
+ std::memcpy(key_pair.private_key, random_32_bytes, 32);
+ ::curve25519_donna(
+ key_pair.public_key, key_pair.private_key, CURVE25519_BASEPOINT
+ );
+ return key_pair;
+}
+
+
+void axolotl::curve25519_shared_secret(
+ axolotl::Curve25519KeyPair const & our_key,
+ axolotl::Curve25519PublicKey const & their_key,
+ std::uint8_t * output
+) {
+ ::curve25519_donna(output, our_key.private_key, their_key.public_key);
+}
+
+
+std::size_t axolotl::aes_pkcs_7_padded_length(
+ std::size_t input_length
+) {
+ return input_length + AES_BLOCK_LENGTH - input_length % AES_BLOCK_LENGTH;
+}
+
+
+void axolotl::aes_pkcs_7_padding(
+ std::uint8_t const * input, std::size_t input_length,
+ std::uint8_t * output
+) {
+ std::memcpy(output, input, input_length);
+ std::size_t padded_length = axolotl::aes_pkcs_7_padded_length(input_length);
+ std::uint8_t padding = padded_length - input_length;
+ for (std::size_t i = input_length; i < padded_length; ++i) {
+ output[i] = padding;
+ }
+}
+
+
+void axolotl::aes_encrypt_cbc(
+ axolotl::Aes256Key const & key,
+ axolotl::Aes256Iv const & iv,
+ std::uint8_t const * input, std::size_t input_length,
+ std::uint8_t * output
+) {
+ std::uint32_t key_schedule[60];
+ ::aes_key_setup(key.key, key_schedule, 256);
+ std::uint8_t input_block[AES_BLOCK_LENGTH];
+ std::memcpy(input_block, iv.iv, AES_BLOCK_LENGTH);
+ for (std::size_t i = 0; i < input_length; i += AES_BLOCK_LENGTH) {
+ xor_block<AES_BLOCK_LENGTH>(input_block, &input[i]);
+ ::aes_encrypt(input_block, &output[i], key_schedule, 256);
+ std::memcpy(input_block, &output[i], AES_BLOCK_LENGTH);
+ }
+ std::memset(key_schedule, 0, sizeof(key_schedule));
+ std::memset(input_block, 0, sizeof(AES_BLOCK_LENGTH));
+}
+
+
+void axolotl::aes_decrypt_cbc(
+ axolotl::Aes256Key const & key,
+ axolotl::Aes256Iv const & iv,
+ std::uint8_t const * input, std::size_t input_length,
+ std::uint8_t * output
+) {
+ std::uint32_t key_schedule[60];
+ ::aes_key_setup(key.key, key_schedule, 256);
+ for (std::size_t i = 0; i < input_length; i += AES_BLOCK_LENGTH) {
+ ::aes_decrypt(&input[i], &output[i], key_schedule, 256);
+ if (i == 0) {
+ xor_block<AES_BLOCK_LENGTH>(&output[i], iv.iv);
+ } else {
+ xor_block<AES_BLOCK_LENGTH>(&output[i], &input[i - AES_BLOCK_LENGTH]);
+ }
+ }
+ std::memset(key_schedule, 0, sizeof(key_schedule));
+}
+
+
+void axolotl::hmac_sha256(
+ std::uint8_t const * key, std::size_t key_length,
+ std::uint8_t const * input, std::size_t input_length,
+ std::uint8_t * output
+) {
+ std::uint8_t hmac_key[SHA256_BLOCK_LENGTH];
+ ::SHA256_CTX context;
+ hmac_sha256_key(key, key_length, hmac_key);
+ hmac_sha256_init(&context, hmac_key);
+ ::sha256_update(&context, input, input_length);
+ hmac_sha256_final(&context, hmac_key, output);
+ std::memset(hmac_key, 0, sizeof(hmac_key));
+}
+
+
+void axolotl::hkdf_sha256(
+ std::uint8_t const * input, std::size_t input_length,
+ std::uint8_t const * info, std::size_t info_length,
+ std::uint8_t const * salt, std::size_t salt_length,
+ std::uint8_t * output, std::size_t output_length
+) {
+ ::SHA256_CTX context;
+ std::uint8_t extract_key[SHA256_BLOCK_LENGTH];
+ std::uint8_t expand_key[SHA256_BLOCK_LENGTH];
+ std::uint8_t step_result[SHA256_BLOCK_LENGTH];
+ std::size_t bytes_remaining = output_length;
+ std::uint8_t iteration = 1;
+ if (!salt) {
+ salt = HKDF_DEFAULT_SALT;
+ salt_length = sizeof(HKDF_DEFAULT_SALT);
+ }
+ /* Expand */
+ hmac_sha256_key(salt, salt_length, extract_key);
+ hmac_sha256_init(&context, extract_key);
+ ::sha256_update(&context, input, input_length);
+ hmac_sha256_final(&context, extract_key, expand_key);
+ /* Extract */
+ hmac_sha256_init(&context, expand_key);
+ ::sha256_update(&context, info, info_length);
+ ::sha256_update(&context, &iteration, 1);
+ hmac_sha256_final(&context, expand_key, step_result);
+ while (bytes_remaining > SHA256_BLOCK_LENGTH) {
+ std::memcpy(output, step_result, SHA256_BLOCK_LENGTH);
+ output += SHA256_BLOCK_LENGTH;
+ bytes_remaining -= SHA256_BLOCK_LENGTH;
+ iteration ++;
+ hmac_sha256_init(&context, expand_key);
+ ::sha256_update(&context, step_result, SHA256_BLOCK_LENGTH);
+ ::sha256_update(&context, info, info_length);
+ ::sha256_update(&context, &iteration, 1);
+ hmac_sha256_final(&context, expand_key, step_result);
+ }
+ std::memcpy(output, step_result, bytes_remaining);
+}
diff --git a/src/libs.cpp b/src/libs.cpp
new file mode 100644
index 0000000..5b9c2aa
--- /dev/null
+++ b/src/libs.cpp
@@ -0,0 +1,5 @@
+extern "C" {
+#include "crypto-algorithms/sha256.c"
+#include "crypto-algorithms/aes.c"
+#include "curve25519-donna/curve25519-donna.c"
+}
diff --git a/tests/test_crypto.cpp b/tests/test_crypto.cpp
new file mode 100644
index 0000000..ed50905
--- /dev/null
+++ b/tests/test_crypto.cpp
@@ -0,0 +1,100 @@
+#include "axolotl/crypto.hh"
+
+#include <cstring>
+#include <iostream>
+#include <iomanip>
+#include <cstdlib>
+
+std::ostream & print_hex(
+ std::ostream & os,
+ std::uint8_t const * data,
+ std::size_t length
+) {
+ for (std::size_t i = 0; i < length; i++) {
+ std::cerr << std::setw(2) << std::setfill('0') << std::right
+ << std::hex << (int) data[i];
+ }
+ return os;
+}
+
+char const * TEST_CASE;
+
+void assert_equals(
+ std::uint8_t *expected,
+ std::uint8_t *actual,
+ std::size_t length
+) {
+ if (std::memcmp(expected, actual, length)) {
+ std::cerr << "FAILED :" << TEST_CASE << std::endl;
+ print_hex(std::cerr << "Expected: ", expected, length) << std::endl;
+ print_hex(std::cerr << "Actual: ", actual, length) << std::endl;
+ std::exit(1);
+ }
+}
+
+
+int main() {
+
+
+
+
+{ /* HDKF Test Case 1 */
+
+TEST_CASE = "HDKF Test Case 1";
+
+std::uint8_t input[22] = {
+ 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
+ 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
+ 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b
+};
+
+std::uint8_t salt[13] = {
+ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+ 0x08, 0x09, 0x0a, 0x0b, 0x0c
+};
+
+std::uint8_t info[10] = {
+ 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
+ 0xf8, 0xf9
+};
+
+std::uint8_t hmac_expected_output[32] = {
+ 0x07, 0x77, 0x09, 0x36, 0x2c, 0x2e, 0x32, 0xdf,
+ 0x0d, 0xdc, 0x3f, 0x0d, 0xc4, 0x7b, 0xba, 0x63,
+ 0x90, 0xb6, 0xc7, 0x3b, 0xb5, 0x0f, 0x9c, 0x31,
+ 0x22, 0xec, 0x84, 0x4a, 0xd7, 0xc2, 0xb3, 0xe5,
+};
+
+std::uint8_t hmac_actual_output[32] = {};
+
+axolotl::hmac_sha256(
+ salt, 0 * sizeof(salt),
+ input, 0 * sizeof(input),
+ hmac_actual_output
+);
+
+assert_equals(hmac_expected_output, hmac_actual_output, 32);
+
+std::uint8_t hkdf_expected_output[42] {
+ 0x3c, 0xb2, 0x5f, 0x25, 0xfa, 0xac, 0xd5, 0x7a,
+ 0x90, 0x43, 0x4f, 0x64, 0xd0, 0x36, 0x2f, 0x2a,
+ 0x2d, 0x2d, 0x0a, 0x90, 0xcf, 0x1a, 0x5a, 0x4c,
+ 0x5d, 0xb0, 0x2d, 0x56, 0xec, 0xc4, 0xc5, 0xbf,
+ 0x34, 0x00, 0x72, 0x08, 0xd5, 0xb8, 0x87, 0x18,
+ 0x58, 0x65
+};
+
+std::uint8_t hkdf_actual_output[42] = {};
+
+axolotl::hkdf_sha256(
+ input, sizeof(input),
+ salt, sizeof(salt),
+ info, sizeof(info),
+ hkdf_actual_output, sizeof(hkdf_actual_output)
+);
+
+assert_equals(hkdf_expected_output, hkdf_actual_output, 42);
+
+} /* HDKF Test Case 1 */
+
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-07-01 12:07:16 +0000